WASHINGTON – Sen. Rob Portman is considering setting up a presidential exploratory committee that would allow him to raise and spend money for a White House bid, according to a source familiar with the Ohio Republican's thinking.

The source, who spoke on the condition of anonymity, said Portman has not made any final decision about his plans for 2016. But Portman's political confidants have talked about what steps the Ohio senator would need to take if he does decide to run for president, including setting up the special fundraising account.

Portman has raised $5 million for his Senate re-election in 2016. He could shift that money to an exploratory presidential committee and use it to build a national campaign operation.

Just this week, Portman visited a critical presidential testing ground — New Hampshire, which holds the first-in-the-nation primary. He has said that while he is currently planning to run for a second term in the Senate, he is also considering a White House run.

"If I don't see other candidates providing that (a strong Republican platform) who I believe could win a general election, I will take a look at it," Portman, of Terrace Park, said last month of the 2016 presidential race. "But right now, I'm planning just to run for Senate in Ohio."

Portman has also said that he's focused on helping Republicans gain control of the Senate in the 2014 elections. He is serving as a top fundraiser for the National Republican Senatorial Committee, the Senate GOP's campaign arm.

In New Hampshire this week, the Ohio Republican said he would not run for both the Senate and the White House simultaneously even though Ohio law would allow him to do so.

Portman was on GOP presidential nominee Mitt Romney's short list to be vice president. Ohio Gov. John Kasich has also been touted as a possible contender in 2016.

Portman. 58, served 12 years in the House before going to work for the White House under President George W. Bush. In the Bush administration, Portman served as U.S. Trade Representative and then director of the Office of Management and Budget.